Sequential Bortezomib, Dexamethasone, and Thalidomide Maintenance Therapy after Single Autologous Peripheral Stem Cell Transplantation in Patients with Multiple Myeloma

We report feasibility and response results of a phase II study investigating prolonged weekly bortezomib and dexamethasone followed by thalidomide and dexamethasone as maintenance therapy after single autologous stem cell transplantation (ASCT) in patients with multiple myeloma. Within 4 to 8 weeks of ASCT, patients received weekly bortezomib and dexamethasone for six cycles, followed by thalidomide and dexamethasone for six more cycles. Thalidomide alone was continued until disease progression. Forty-five patients underwent ASCT. Forty patients started maintenance therapy; of these, 36 patients received four cycles, and 32 completed six cycles of maintenance bortezomib. Of these 40 patients, nine (22%) were in complete response (CR) before ASCT, 13 (32%) achieved CR after ASCT but before bortezomib maintenance therapy, and 21 (53%) achieved CR after bortezomib maintenance therapy. Nine patients not previously in CR (33%) upgraded their response to CR with bortezomib maintenance. At 1 year post-ASCT, 20 patients achieved CR, and two achieved very good partial response. Twenty-seven patients experienced peripheral neuropathy during bortezomib therapy, all grade 1 or 2. Our findings indicate that prolonged sequential weekly bortezomib, dexamethasone, and thalidomide maintenance therapy after single ASCT is feasible and well tolerated. Bortezomib maintenance treatment upgraded post-ASCT CR responses with no severe grade 3/4 peripheral neuropathy.